Radiant heat seal



2 Sheets-s l &

A TTORNEY n u r.uw| :N. 1

I Sept 1944.

RADIANT HEAT S Filed Dec 6, 9

Sept 1944- H. E. HALLMAN 2,358,455

RADIANT HEAT SEAL Filed Dec. 6, 1939 q 2 Sheets-Sheet 2 Fgr. j

IN VEN TOR.

IMROLD E. HALLNAN.

A TTORNEYS.

Patented Sept. 19, 1944 UNITED STATES PATENT OFFICE RADIANT HEAT SEAL Harold E. Hallman, Catonsville, Md.

Application December 6, 1939, Serial No. 307,794

3Clalms.

sealing the longitudinal seam in the formation of wax coated paper bags.

It relates more particularly to a machine comprising in combination, a former over which continuously travels a web of wax coated paper upon and over which the edges of the wax coated paper are folded and placed in juxtaposition to each other after a suitable adhesive has been applied to the surface of one of the edges which is to extend beneath and adjacent to the surface of the opposite edge.

In its progress over the former after the adhesive has been applied to the appropriate edges placed in juxtaposition to each other, the wax coated edge passes beneath the source of radiant heat, the heat striking through the wax coated paper, causing the wax to runand melt sufllciently to permit the adhesive to strike through the wax coating and permit the adhesive to bond the paper together.

The former preferably will then have a slot beyond the source of radiant heat so that there will be no tendency of any wax which might have been melted to cause the web to stick to the former and, if desired, a tension roll may be mounted in order to exert a yielding pressure or tension on the web so that the edges might be glued together.

In the manufacture of wax coated paper bags and similar articles, the problem of obtainin a proper seal of the wax paper has presented many difliculties. It is necessary that this longitudinal seam have strength and such strength cannot be obtained simply by heat sealing the wax coated paper.

When glue is applied to facilitate the joining operation and to make the joint more secure, the glue fails to obtain a suflicient grip upon the wax coated paper and it is thus dimcult to get proper results. It is known that to obtain the proper seam the wax must be sufilciently melted so that the applied glue strikes through the wax to the paper and firmly bonds the paper to effect a seam.

However, when heat is applied with pressure, the pressure squeezes the glue out of its proper position and a. proper seam is not readily obtainable. If, on the other hand, no pressure is used thereon, then a proper joint is not obtained because the edges are not pressed into close enough relation to each other to permit the glue to strike through. Very frequently wax coated papers of various kinds and particularly of a type used in forming bags are translucent or transparent and will therefore readily permit heat rays to pass through.

Accordingly, it is my intention, in this invention, to make use not necessarily of conducted heat but of radiant heat for the purpose of causing the melting of the wax and the striking through of the glue through the wax into the paper. It will not be necessary to bring the wax paper directly into contact with the heat source, but it will be possible by merely passing the paper beneath a source of radiant heat or close to such a source that the radiant heat rays will strike through the transparent paper to the wax below and cause that wax to melt and run sufiiciently to permit the glue to strike through to the principal web and bond the papers together.

In order to further insure that the glue strikes through and in order to prevent the wax from running out upon the free edges, a yielding pressure may be applied to the joined portions immediately after the application of heat and such yielding pressure which can be readily regulated will cause the edges to approach each other under tension sufficiently to join the edges together without exerting such extreme pressure as would drive the wax out of its proper contact. Further it becomes useful to so adjust and arrange the former that there will be no possibility of the melted wax causing the web to stick to the former and thus impeding or disrupting the manufacturing operation.

It is an object of my invention therefore to provide a novel apparatus for imparting radiant heat for the purpose of effecting a seal between wax coated papers when an adhesive is employed therebetween.

It is a further object of my invention to provide, in a novel apparatus for joining wax coated papers with glue between, a source of radiant heat which will cause the wax to run sufficiently to permit the glue to strike through to the papers, followed by a means for applying yielding pressure to insure the formation of the joint.

It is a further object of my invention to provide an apparatus comprising a former and source of radiant heat and a means for obtaining yielding pressure upon the joint to be formed immediately after theapplication of such heat.

Other objects of my invention will become apparent from the following description and drawings, in which:

Figure 1 is a top plan view showing the general organization 'or relationship of the wax coated web, the former, the source of radiant heat, the yielding tenslonal device and the means Figure 3 is a cross sectional view taken alongline 33 of Figure 1.

Figure '4 is a cross-sectional view taken along line 44 of Figure l.

Referring now to Figures 1 and 2, the web I is drawn along the former H in the manner hereinafter described. The web Ill originally commences the process at the right hand side of the figure in the form of a flat wax coated sheet preferably either translucent or transparent. By gluing and folding means well known in the art, the edges l3 and .ll of the web H) are folded up in the manner shown about the former II as the sheet continues to move forward, that is, towards the left. At the same time, an adhesive stripe I5 is applied to the longitudinal area adjacent the edge l3 which lies beneath the edge I4 in the folded position as seen at It. The sheet as it is continuously drawn onwardly passes beneath a source of radiant heat IT.

This source of radiant heat I! is preferably of the open flame type wherein a source of heat preferably an electrical resistance coil I8 is wound about a .core l9 and partially encased within a cylinder 20, the interior of which is polished, the said cylinder being open along the side thereof adjacent the edge |3l4 of the web passing beneath. The exact organization of this cylinder is hereinafter described. By an open flame type of heater is meant one wherein the actual heating element or heat source is directly exposed to the member to be heated and where substantially all of the heat transferred between the actual heating element or heat source and the member to be heated is by radiation rather than by conduction.

Thereafter, as seen in Figures 1 and 2, the folded web passes onwardly beyond the roll 2| which rides in a recess 22 in the former, the said roll projecting beyond the upper surface of the former into the recess so that the paper is bent out of its position beneath the roll at said recess. The recess 22 communicates with a slot 23 in the former, the said slot 23 being also clearly visible in Figure 4.

The folded web is drawn along the former as seen in Figures 1, 2 and 4, by means of the pressure rollers 30, 30 which register with the cut out portion 3|, 3| of the former so that the edge of the folded web 32 (Figure 4) maybe fed directly between opposed rolls. 30, 30 andpushed on.

It will be seen that while whatever heating operations are performed oroccur at the center of the former and hence at the longitudinal center of the folded web, the feeding operations represented by the rollers 30, 30 occur at the margins of the former and hence at the margins 32 of the folded web and hence any pressure thereat since it is not in proximity to any wax which may have been melted or to any adhesive will not deleteriously affect the finished product.

As before pointed out, the purpose of this invention and of the apparatus herein described is to first apply the adhesive to the edge as shown, then to fold the two edges together, one above the other, then to heat the edges so that the wax will melt sufliciently to permit the adhesive to strike through. As seen in Figure 3,

aasaeuc the source of radiant heat It is not at any time directly in contact with the edges It or ll which are to be glued together. The some of heat It, however, is of the open flame type and is contained within the cylinder 20 having the opening 4| and a highly reflective interior surface 4| whereby the heat generated by the heat source It is reflected anad directed upon the areas I3 and It to be joined. There is no pressure whatever at the time heat is applied.

Obviously it will be seen that the cylinder 20 need not necessarily be truly cylindrical in form.

systems may be used to effectively localize the heat rays and to insure that they impinge upon and strike through to the proper area.

Also, as above pointed out, in the usual case the wax coated paper to be joined in the manner herein described is either transparent or translucent so that even without direct contact, the radiant heat is enabled to strike through the transparent or translucent sheet to melt the wax to permit the adhesive to bind together the sheets.

Thereafter, whatever pressure is desired is created by the roll 2| registering with the recess 22 wherein the sheet at the joint is not pressed against the former but is bent out of the line which it would normally follow and thus the tendency of the sheet to naturally return to its original position provides a sufficient yielding pressure to insure that the adhesive will strike through themelted wax to secure the sheets together. When the sheet then passes beneath and beyond the roll 2| in the ordinary speed of the process, the wax may not yet have had sufficient time to become hard enough to prevent its running or sticking. If it is permitted to contact or collect .upon the former, then the adhesion of the wax to the former would seriously impede the progress of the web and tend to wrinkle or even destroy it.

According y, the slot 23 (Figures 1, 2 and 4) immediately beneath the joint removes any portion of the former to which the wax might conceivably adhere and gives the web sufficient time to dry or re-harden while the web is travelling alone. Accordingly the slot 23 should be of sufflcient length to permit the wax to re-harden and the slot 23 may thus, if desired, be continued to the end of the former where the moving web enters upon the succeeding processes of bag formation.

If desired, also, instead of slot 23 a cooling medium may be used, not necessarily in contact with but adjacent to the joint in order to hasten the re-hardening process. This cooling medium may be provided either in the slot 23 or by members adjacent to or supported immediately above that part of the web which extends above the slot 23. Thus for instance, capsules containing dry ice may be mounted in the slot 23 or upon suitable brackets contained therein or the roller 2| which applies the initial yielding pressure which finally effects the seal at the joint may be followed by similar hollow rollers which may be filled with solidified carbon dioxide or various mechanical refrigerating devices may be used in proximity to the joint at a point immediately after the initial yielding pressure is applied.

I have even found it practical to apply dry ice in the roller 2i since the pressure I seek is applied not so much directly by the roller 2| as by the fact that that roller causes the paper to be deflected out of its normal position and the tension generated in the paper by its resistanceto such deflection exert-s the pressure necessary to cause the glue finally to adhere to opposite sheets of 9 1 By the time then that the Joint is actually in contact with the roller 2 I the glue has already struck through the melted wax and there is no harm done at that time if the wax is suddenly chilled so that the sealing may actually take place by the roller 2i which is the cause of the yielding pressure which I find useful.

Nevertheless, in high speed operation I prefer. in order to insure the eifectuation of a complete bond that the chilling operation should take place after the paper has passed the roll 2|.

It is obvious of course that many modifications oi the particular apparatus andmethods shown herein maybe used. Thus mymachine and method is not necessarily limited to a particular type of heating device. Any open type heating device generating radiant heat which might be directed to a particular area may be used. I need not by the use of this device, have actual contact between the heat element and the sheet itself. In

this way any possibility of burning the sheet itself is obviated. Particularly when the sheet itself is transparent or translucent and thus permits the heat to strike through to the wax coating and melt the same: a process using radiant heat of this type instead of conductive heat generated by contact becomes even more useful.

The application of the yielding pressure may take many forms. However, I prefer that the pressure following the application of heat be a yielding one so that whatever was is melted will not be forced to flash out upon the joint and thus make the Joint uneven.

Although I have particularly described my inunion of any coated materials and more especially to any sheet materials coated with thermosensitive materials. It will be noted that the method and apparatus herein shown efl'ect the parting of the heat sensitive coating on .the sheet material to allow the penetration of the added adhesive and that this would be the efl'ect with any coat,- ing such as cellulose derivatives, synthetic resins or rubber compounds or any suitable coating materials used in conjunction with paper, regenerated cellulose sheet material including Cellophane, pliofilm, sylph-wrap, paper or any suitable sheet material.

Many other variations and modifications oi' the apparatus and method herein described will now be obvious. I prefer, however, to be limited not by the specific disclosure herein but only by the appended claims.

I claim:

1. An apparatus of the character described comprising a former, a source of radiant heat directed toward said former, and a recess in said former immediately beyond said source of radimeans for directing the heat radiating therefrom.

upon a confined area of said former; a recess ant heat, and a pressure member registering with said recess.

2. An apparatus of the character described comprising a former; an open flame heat source;

in said former immediately beyond said source of radiant heat; and a pressure member registerin with said recess..

8. An' apparatus of the character described. comprising a former; a'recess in said former; a pressure member registering with said recess; a source of radiant heat immediately before said recess; said heat source comprising an open flame type heater adjacent said former; and an internally polished sheath therefor having an opening directed toward. a .conflned area of said principles involved are the application of radiant former.

- HAROLD E. HALIMAN. v 

